What is the essence of phagocytosis?

Phagocytosis (like pinocytosis) is a type of endocytosis.
In this process, the cell absorbs particulate matter.
During phagocytosis, the cell membrane envelopes a solid particle, forming a membrane vesicle. After that, the vesicle merges with the lysosome, which carries the necessary enzyme. The particle is released by the lysosome enzyme. The remaining substances remain in the cytoplasm of the cell and are used for its vital activity.
In unicellular organisms, the process of phagacytosis is a way of feeding the body.
The process of phagacytosis also provides a protective function, since in this way not only the breakdown of food occurs, but also the fight, for example, of leukocytes, with pathogens.